The aim of this study is to investigate microstructural defects in drill bit cutting elements, including milled teeth and WC–Co cemented carbide inserts, to clarify their morphology, chemical–phase characteristics, and potential contribution to manufacturing-related defects. To achieve this goal, the study applied a combined approach based on optical microscopy and scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy (SEM–EDS). First, the study examined surface and microstructural features, such as pores, depressions, and local heterogeneities formed during manufacturing. Then, it conducted detailed SEM–EDS analyses of selected local regions, including crack initiation sites. As a result, the study revealed that cutting elements from a defective batch exhibit pronounced microstructural and chemical–phase heterogeneity. Moreover, defect regions show local redistribution of the WC carbide phase and the cobalt binder, as well as increased oxygen content, indicating the presence of thin oxide and adsorbed surface layers. Consequently, these microstructural features may act as local stress concentrators and reduce the structural integrity of cutting elements already during manufacturing. The benefits of this study include improved understanding of defect formation mechanisms and guidance for optimizing technological processes in drill bit production.
Abdurakhmonov et al. (Fri,) studied this question.